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production of first commercial halftone screens

...a crossline halftone was produced using a single-direction screen, by making half the exposure with the screen in one position and half with the screen rotated a quarter turn. Two brothers, Max and
Louis Levy, of Philadelphia, in 1890 produced the first commercial halftone screens. The Levy brothers coated selected plates of high-quality optical glass with a lacquer, in which parallel lines...